1. Field
The present field relates to the field of the manufacture of a mold for a tire comprising a plurality of cavities which are able to mold closure devices in one or more groove(s) of this tire. More particularly, the field relates to the manufacture of a mold formed from a plurality of molding elements.
2. Description of Related Art
Document WO 2010146180 discloses a vulcanizing mold for a tire comprising a plurality of molding elements. Each molding element is delimited by two edges in contact with two other adjacent molding elements so that once the molding elements are in contact with one another, all of these molding elements together allow all or part of the tread of the tire to be molded.
Each molding element comprises a base and a bar projecting from this base. The base is intended to mold the tread surface of the tread of the tire and the bar is intended to mold a groove in the tread of this tire, i.e. a cut of a width greater than or equal to 2 mm.
It is known that, in the contact patch in which the tread is in contact with the road surface, each groove forms a resonance tube with this road surface. This resonance tube amplifies the running noise of the tire, and this may be unpleasant for people situated inside the vehicle and/or outside this vehicle.
In order to limit the intensity of this resonant noise, it is known practice to provide the grooves with special closure devices also referred to as “flexible walls” or “flaps”. These closure devices take the form of thin blades. These blades partially close off the cross section of the grooves when the tire is running on a dry road surface. When it is running on a wet road surface, the blades flex under the action of the flow of water, so that this water can be removed from the contact patch between the tire and the road surface. The grip of the tire on the road surface is thus maintained even when running under severe wet conditions. Such an example of a closure device is notably known from document WO 2010063749.
To mold these closure devices, document WO 2010146180 discloses a molding element comprising a bar provided with housings designed to accept inserts, each insert comprising a molding cavity for molding a closure device. The bar of the molding element is therefore discontinuous because it is punctuated by the housings that accommodate the inserts.
For certain types of tire such as winter or snow tires it is known practice to provide the tread with sipes. A sipe means a cut of a width less than 2 mm. These sipes are molded by sipe blades that project from the base of the molding element. To improve the mechanical strength of these sipe blades it is generally contrived for these to be formed as one with the bar of the molding element, i.e. for the sipe blades and the bar to be produced at the same time during one and the same molding operation. Now, the inserts are manufactured during a step which is different from the step of molding the sipe blades and the bar. Thus, if sipe blades are to be positioned in line with inserts, for example because of a special design of the tread, it is necessary to resort to an additional step of welding these sipe blades to the inserts. This leads to additional manufacturing costs.
It is therefore an object of embodiments of the invention to improve the overall mechanical strength of a mold made up of several molding elements and comprising cavities for molding closure devices, while at the same time optimizing the cost of manufacturing this mold.